| Switching voltage regulator, with its distinctive features of high level of integration, simple peripheral circuit and high efficiency, has been widely used in many electronic products. DC-DC converter is one of the important parts of switching voltage regulator. Based on the background of applying portable electronic products with battery power supplies, the paper focuses on researching and designing a kind of DC-DC boost converter by voltage mode of pulse-skipping modulation (PSM). The converter has some advantages such as easy realization of circuit, precise voltage output, high efficiency conversion, and etc.The DC-DC boost converter is designed systematically in the paper. The circuit is divided into the power stage, oscillator and voltage regulator. The paper mainly focuses on the oscillator and voltage regulator. We designed a relaxation oscillator with 1MHZ frequency and 94% duty cycle, which is composed of hysteresis comparator and charge and discharge circuit with constant current. The hysteresis comparator has better anti-jamming and the charge and discharge with constant current can get high level of power supply rejection ratio (PSRR) and temperature stability. The function of voltage regulator is to make 24V steady voltage output. PSM circuit is comprised of hysteresis comparator and D trigger. It has characteristics of simple configuration, easy realization, and high efficiency under light load.The oscillator and the whole circuit of DC-DC boost converter are simulated using Hspice. The results indicate that the maximum frequency error of the ocsillator is 3% within the temperature rang (-40℃ to 85℃), and voltage range (2.6V～5.5V). Monte-Carlo analysis reports show that the frequency precision of oscillator is within ±14%. The simulation results also reveal that the DC-DC boost convertor has a steady output voltage of 24V. When the value of filter capacitance is 10uF, the ripple of output voltage is within ±1%. |
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